Many modeRN mobile devices such as smartphones contain processors with speeds exceeding 600 MHz, and it is contemplated that future generation products will be even faster, and will have even more processing capabilities. In order to fully utilize the processing capabilities of such a device, certain applications need to send and receive large amounts of data over a wireless network. In order to maximize both the mobility of the device and the processing capabilities of the device, the wireless network will have both a large range and a high data transfer rate. One common solution used in the art is to have the device connect to a cellular phone network such as CDMA, GSM, GPRS, or EDGE, or to a wireless network such as a WiFi network. Both these solutions, however, have limitations. Cellular phone networks do not provide a high enough data transfer rate to run certain applications, and WiFi networks have limited ranges (typically less than 200 meters), significantly limiting the mobility of a device.
In light of the shortcomings of the aforementioned network architectures, a new wireless network protocol called Worldwide Interoperability for Microwave Access or “WiMAX” has emerged. WiMAX has a range comparable to cellular phone networks and data-transfer rates comparable to WiFi networks. The base stations in a WiMAX network can frequently transmit data over a greater than 10-mile radius. Therefore, in order to fully utilize the base station's transmission range, a mobile device must also be able to transmit at a signal strength sufficient to cover the same range. For instances when a mobile device is not at the outer limits of a base station's transmitting range, less transmitting signal strength is required. In order to reduce battery consumption in a mobile device, it is therefore desirable for a mobile device to be able to dynamically adjust its transmitting signal strength as its distance from a base station changes.
In order to establish an initial connection between a WiMAX base station and a mobile device, the base station can send out a broadcast message containing information identifying the base and network information, and upon detecting a broadcast message, a mobile device can send out a known sequence called a ranging sequence to the WiMAX base station. When initially sending out the ranging sequence, the mobile device does not know the parameters needed to determine an appropriate transmission strength. One possible solution is to always send out the initial ranging sequence at a maximum power level. This solution, however, has several shortcomings, such as unnecessary battery power consumption and the potential creation of unnecessary interference for other wireless signals. Additionally, the IEEE 802.16e standard governing the WiMAX protocol dictates that a device must revert to a minimum signal transmission strength if a transmission at maximum strength is unsuccessful. Reverting to minimum signal strength could lead to increased network entry times in instances when the initial ranging sequence does not successfully establish a network connection. Initially transmitting the ranging sequence at an insufficiently low signal strength also can increase network entry time due to repeated unsuccessful network entry attempts.
Therefore, there exists in the art a need for an efficient algorithm for determining the initial power level at which to transmit the ranging signal. Additionally, there exists in the art a need for an algorithm for determining how to adjust the signal strength of the transmission should the first transmission not result in a network connection. Aspects of the present invention include an algorithm that addresses these needs by increasing the probability of establishing a connection with the base station while at the same time reducing unnecessary power consumption by the mobile device.